1. Field of the Invention
This invention relates generally to an irrigation system, and more particularly to a subterranean irrigation system for controlled irrigation and fertilizing of large areas of plants.
2. Description of Related Art
Irrigation is commonly used in the nurturing of plants outdoors to supplement precipitation. Most irrigations systems supply water at the soil surface although subterranean irrigation systems have been proposed. Fertilization is also most commonly performed by application of fertilizer at the soil surface.
U.S. Pat. No. 4,224,048, Pendergast, entitled: "Osmotic Fertilizer Product and Fertilization Method", discloses a tubular membrane having fertilizer packed therein. This tube is buried in the vicinity of the roots of plants to be fertilized. During surface watering, water passes through the tube wall by osmosis. As the soil dries, dissolved fertilizer leaves the tube and fertilizes the plants.
U.S. Pat. No. 4,235,561, Peterson, entitled: "Subterranean Irrigation Means and System", discloses the use of porous or semipermeable pipe arranged in a network to water and fertilize plants over a large area.
In carrying out the present invention we prefer to use flexible, hollow, semipermeable, cellulose acetate fibers formed into coils of constant dimensions.
U.S. Pat. Nos. 3,423,491, McLain et al.; 3,873,653, Meinecke et al.; and 4,035,459, Kesting all describe the fabrication of such fibers.